Colour

Colour Rendering Index

Recent spectral measurements for the MONOFLEX range of PCBs can be found below. This shows the exact correlated colour temperature (CCT) of each light source measured and the corresponding Colour Rendering Index (Ra). The results show the standard 2700K Samsung (S30 & S60) LED to have an impressive 87 Ra. Yet more impressive data from the Samsung LM561B LED!

Custom Packaged

Osram Duris E3

Sansung LM561B

LED Type

C42-2200K

C42-2700K

C112-2700K

C112-3000K

S30-2700K

S30-2700K-IP65

S60-2700K

CCT

2215

2905

2714

3086

2737

2664

2794

CRI Ra

80

86

85

85

87

86

87

Colour Consistency

Colour consistency is an extremely important aspect of LED lighting, especially in linear lighting applications where we may typically have hundreds of LEDs, within different architectural details, within a single space.

During the various manufacturing stages - from LED die through to final packaged chip – different batches with inevitably has slight variations of colour appearance, colour temperature, lumen output, etc.

To combat this issue manufacturers measure the photometric characteristics of the LED during manufacture and separate them into groups called bins.

Bin classifications differ from manufacturer to manufacturer and there may be a series of rankings for the luminous flux and colour, with sub-division of the colour bin into smaller bin lots based on CIE X,Y chromaticity co-ordinates.

Therefore as a black-body radiator is heated the colour appearence of the emitted light will change from a warm red-white glow at low temperatures to a bright blue-white at high temperatures. The curved line through the centre of the CIE diagram below is refered to as the black body locus, the isotemperature lines crossing the black body locus define the correlated colour temperatures, therefore unless the colour temperature of the measured light source falls directly on the black body locus, it should be considered as a Correlated Colour Temperature (CCT).

The measure is therefore used to describe the appearance of artificial light sources in comparison to the black body through plotting the X Y Chromaticity co-ordinates on the CIE diagram, as shown below. If we consider the extend of the isotemperature lines crossing the black body locus, we can see that a light source with the same measure CCT could actually have slightly different spectral composition and therefore colour appearance.

This is the reason why all light source with a 3000K or 4000K CCT are not exactly the same. Ideally you want to be selecting a light source with chromaticity co-ordinates as close as possible to the black body locus for the best and most accurate colour appearance, when compared to a black body radiator.

MONO LEDs are carefully selected from bins as close as possible to the black body locus for each selected colour temperature.